Heatmaps are the big new feature in the new version of Psychostats, the stats package we use for our game stats, and I must say, in my opinion, they are pretty spectacular. They are a pain to set up, so it is going to be a long time before we have heatmaps for all our maps, but in the meantime you can check out the first couple I have created for our Natural Selection stats.
Just go to the maps page, click on either co_core or co_faceoff, and click the heatmap link in the upper right corner.